Liam McIntyre is stronger than ever as he enters his second season as the heroic gladiator, thanks to an all-body regimen, smart nutrition—and Dirty 30s

Real gladiators were big, well-fed men, says Barry Strauss, Ph.D., a professor of history and classics at Cornell and author of The Spartacus War. “They looked a little like sumo wrestlers with spare tires. One guess is that the girth protected them from wounds,” he says.

There are no gladiator guts on Spartacus. But these televised warriors have a philosophy similar to that of the ancients: Nutrition rules, whatever your training. (Fuel your muscles with 5 Protein-Packed Gym Snacks.)

To maintain his body, McIntyre eats a bowl of oats with protein powder for breakfast; other meals focus on lean protein (chicken or fish) and vegetables, and maybe some good carbs like a sweet potato or whole-grain rice. “Rinse and repeat,” he says.

Once a week, McIntyre takes 2 hours to eat whatever he wants.

“You say, ‘To hell with it’ and cheat, but then you try to fight vomiting—and you realize why you cheat only once a week. It’s not a cheat day; it’s 2 hours where I can have as many calories as I want,” McIntyre says. “I’ll have pizza, maybe a burger. My girlfriend likes baking, so every Friday I have cheesecake waiting for me during those 2 hours.”

Between seasons, McIntyre had a few months during which he could’ve let his nutrition go before ramping up for preseason training. Didn’t happen.

“The funny thing is that I tried to let it go, but I felt awful, absolutely horrible. The old me wanted to eat badly, but that didn’t last long,” McIntyre says. He needed to eat right not only for aesthetic appeal but also to maintain maximum energy and training strength—and for handling the demands of fight scenes.

ANCIENT GLADIATORS HAD the ultimate motivation to keep in shape—staying alive. McIntyre has a similar philosophy, though the stakes aren’t quite as high.

“I’ve always been stubborn. I don’t like losing. I don’t like failing at anything. So the job at hand, you find a way to do it. “The key to motivation,” he says, “is the people around you.”

The final season, Spartacus: War of the Damned, premieres January 25, 2013, at 9 p.m. EST. PLUS: The 2013 Spartacus Workout—from Men's Health and Starz—is now available on DVD! Discover how to lose fat faster than ever with our exclusive two-DVD set. Click here to buy!